Stadium: Court 9 Round: 25 Ground: Clay
| French Open MD | 2021/06/01 12:45 | Koolhof/Rojer v Krajinovic/Lajovic | 6-4,4-6,6-2 |
| ATP Rome MD | 2021/05/14 08:00 | Arevalo/Middelkoop v Koolhof/Rojer | 2-6,7-6,10-5 |
| ATP Rome MD | 2021/05/13 08:00 | Behar/Escobar v Koolhof/Rojer | 6-4,3-6,8-10 |
| ATP Rome MD | 2021/05/11 11:40 | Cecchinato/Travaglia v Koolhof/Rojer | 6-4,1-6,7-10 |
| Davis Cup | 2019/11/20 16:05 | Murray/Skupski v Koolhof/Rojer | 6-4,7-6 |
| French Open MD | 2021/06/02 09:00 | Bedene/Withrow v Koepfer/Ruusuvuori | 1-6,4-6 |